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[en] This paper proposes a 10 μm thick oxide layer structure, which can be used as a substrate for RF circuits. The structure has been fabricated by anodic reaction and complex oxidation, which is a combined process of low temperature thermal oxidation (500 deg. C, for 1 h at H2O/O2) and a rapid thermal oxidation (RTO) process (1050 deg. C, for 1 min). The electrical characteristics of oxidized porous silicon layer (OPSL) were almost the same as those of standard thermal silicon dioxide. The leakage current through the OPSL of 10 μm was about 100-500 pA in the range of 0-50 V. The average value of breakdown field was about 3.9 MV cm-1. From the X-ray photo-electron spectroscopy (XPS) analysis, surface and internal oxide films of OPSL, prepared by complex process were confirmed to be completely oxidized and also the role of RTO process was important for the densification of porous silicon layer (PSL) oxidized at a lower temperature. For the RF-test of Si substrate with thick silicon dioxide layer, we have fabricated high performance passive devices such as coplanar waveguide (CPW) on OPSL substrate. The insertion loss of CPW on OPSL prepared by complex oxidation process was -0.39 dB at 4 GHz and similar to that of CPW on OPSL prepared by a temperature of 1050 deg. C (1 h at H2O/O2). Also the return loss of CPW on OPSL prepared by complex oxidation process was -23 dB at 10 GHz, which is similar to that of CPW on OPSL prepared by high temperature
[en] The recycling metal fuel technology is a core technology that enables the recycling of TRU fuel that separates highly toxic materials from spent fuel and connects Pyro processing with fast reactor. The objective of this project is to develop a manufacturing technology for recycled metal fuel slugs and remote manufacturing technology from 2013. 03 to 2017. 02, to develop the manufacturing technology of metal fuel slugs, to develop remanufacturing technology for recycling metal fuel, to evaluate the performance of recycling metal fuels, development of barrier cladding tube manufacturing technology. As a result of the study, it was possible to obtain the metal fuel slugs manufacturing technology of 13 ea / batch of high rare earth metal fuels slugs, and the development of the anti-volatile casting method of Am in metal fuel by using Sm and Mn, In addition, the development of remote manufacturing technology of metal fuel remote manufacturing equipment design, remote design of additional facilities and simulation performance test, ATR irradiation test of cladding including Cr barrier, transient hot cell simulation test, fuel performance evaluation results were obtained. We have succeeded in plating a 20μm thick Cr layer on the inner surface of HT9 cladding with a length of 150mm using electrolytic plating method. We confirmed the FCCI prevention performance. We fabricated a thin liner and mother tube to prepare a liner cladding preliminary prototype having 100μm nominal thickness by drawing. The results of this study will be used as a preliminary study for the development of TRU fuel fabrication technology that will be continuously studied and will be used as the basic technology for securing stability, nuclear non-proliferation and economical efficiency of the recycling metal fuel manufacturing facility to be constructed later.
[en] The irradiation test for HANA claddings conducted and a series of evaluation for next-HANA claddings as well as their in-pile and out-of pile performances tests were also carried out at Halden research reactor. The 6th irradiation test have been completed successfully in Halden research reactor. As a result, HANA claddings showed high performance, such as corrosion resistance increased by 40% compared to Zircaloy-4. The high performance of HANA claddings in Halden test has enabled lead test rod program as the first step of the commercialization of HANA claddings. DB has been established for thermal and LOCA-related properties. It was confirmed from the thermal shock test that the integrity of HANA claddings was maintained in more expanded region than the criteria regulated by NRC. The manufacturing process of strips was established in order to apply HANA alloys, which were originally developed for the claddings, to the spacer grids. 250 kinds of model alloys for the next-generation claddings were designed and manufactured over 4 times and used to select the preliminary candidate alloys for the next-generation claddings. The selected candidate alloys showed 50% better corrosion resistance and 20% improved high temperature oxidation resistance compared to the foreign advanced claddings. We established the manufacturing condition controlling the performance of the dual-cooled claddings by changing the reduction rate in the cold working steps
[en] Fretting wear tests were carried out in room and high temperature water in order to evaluate the wear properties of new zirconium nuclear fuel claddings (K2∼K6) and the commercial claddings (M5, zirlo and zircaloy-4). The objective is to compare the wear resistance of K2∼K6 claddings with that of the commercial ones at the same test condition. After the wear tests, the average wear volume and the maximum wear depth were evaluated and compared at each test condition. As a result, it is difficult to select the most wear-resistant cladding between the K2∼K6 claddings and the commercial ones. This is because the average wear volume and maximum depth of each cladding included between the scattering range of measured results. However, wear resistance of the tested claddings based on the average wear volume and maximum wear depth could be summarized as follows: K5 > zircaloy-4 > (K2,K3) > (K4,M5) > K6 > zirlo at room temperature, zircaloy-4 > K5 > (K3,K4,zirlo) > (K2,K6) > M5 at high temperature and pressure. Therefore, it is concluded that K5 cladding among the tested new zirconium alloys has relatively higher wear-resistance in room and high temperature condition. In order to examine the wear mechanism, it is necessary to systematically study with the consideration of the alloying element effect and test environment. In this report, the wear test procedure and the wear evaluation method are described in detail
[en] In this study, SiC was coated on the surface of Zry-4 cladding to improve the oxidation protectiveness. In the coating of SiC onto Zry-4, the prime concern was adhesion at an elevated temperature. Here, a 70 keV N ion beam was irradiated onto a SiC coating layer of ∼100 nm in thickness; this was deposited via the e-beam evaporation method. Additional coating to a target thickness was then carried out. The films deposited without ion-beam mixing (IBM) often peeled-off at an elevated temperature, while the IBM SiC film always adhered to Zry-4, even after heating to ∼1000 °C; at such a temperature, however, cracks formed in the film. X-ray photoelectron spectroscopy (XPS) analysis showed that the deposited SiC film contained about 20 at.% of O, while after annealing in air, 76 at.% of O was found on the surface layer. This implied that both the surface of SiC film and Zry-4 in the crack lines were oxidized. Comparing the Zr3d peak positions across the interface, a shift of binding energy by ∼1 eV was detected, representing that, in view of favorable thermodynamics, SiC/Zry-4 seems to be an acceptable system to apply IBM. To heal the crack, the process of IBM for a 1 μm thick coating and annealing was repeated. High-resolution field emission secondary electron microscopy (FE-SEM) showed that the crack lines, the main places at which oxidation occurred, were gradually covered as the process was repeated, ensuring enhanced oxidation protectiveness.
[en] Microstructure characterization, texture measurement and evaluation of corrosion properties were performed at various manufacturing steps from TREX to final tube for advanced Zr fuel cladding tubes. From the result of corrosion test in steam at 400 .deg. C, it was found that the corrosion behavior at the early stage was highly affected by crystallographic texture and the corrosion resistance increased when (0002) texture normal to the corrosion surface was well developed. However, the effect of texture on the corrosion behavior decreased when oxide thickness increased. It is suggested that the texture of Zr alloy plays an important role in corrosion behavior at the early stage though the corrosion behavior is dominated by oxide characteristics when thick oxide was formed
[en] Microstructural characteristics and corrosion properties were evaluated for the intermediate products in the manufacturing process of advanced nuclear fuel cladding tubes containing high Nb. The microstructures of the intermediate products at each manufacturing steps were found to be almost identical due to the same annealing condition. The precipitates observed in the intermediate products were β-Nb and Zr3Fe-type precipitate containing Nb. Texture measurement reveals that the (0002) pole intensity in the radial direction increased as the manufacturing step proceeded. It was found that the corrosion behavior was not significantly affected by the texture but highly dependent on the annealing temperature. Therefore, it is indicated that the corrosion behavior of Zr alloy containing Nb more than solubility was controlled mainly by the Nb contents and the Nb-containing precipitates
[en] Blanket-shield system in ITER is the component where it directly is faced with high-heat plasma. Function of blanket is to sustain extremely high temperature environment as well as to remove heat flux generated its surface. It mainly consists of plasma facing part, heat sinking part and structural part. Plasma facing part is made of armour materials such as beryllium, tungsten and carbon fiber composite. Heat sinking part is made of copper alloy to maximize heat transfer into flowing coolant inside of blanket. Structural material is used in 316LN stainless steel. As joining such dissimilar materials emerged as an issue, many developed countries have spurred the development of joint technology. This technical report was focused on the activities of EU regarding joining beryllium, copper and stainless steel. EU have adopted to Hot Isostatic Pressing (HIP) to join beryllium, copper and stainless steel. Although brazing process is not actively investigated compared as HIP, it still investigated in some countries to support HIP. Fabrication of mock-up is accomplished by CEA in France to finish small scale mock-up in 1996, medium and large scale mock-up in 1997. In recent, FRAMATOME in EU has focused on manufacturing prototype used for ITER
[en] Manufacturing technology of recycled metal fuel is a technology to produce SFR fuel after Pyro processing of spent nuclear fuel. Because all the manufacturing process is performed in hot cell facility due to high radiation material of recycled nuclear fuel, it is important to develop the remote fabrication technology. In this study, a surrogate metal fuel slug was manufactured by performing remotely casting test to verify the feasibility of manufacturing a fuel slug using an remote engineering-scale metal fuel fabrication equipment for the purpose of manufacturing a recycled metal fuel slug in a hot cell. As a result of the casting test, it was confirmed that 78 simulated fuel slug, which is the maximum surrogate fuel slug in the batch, were made remotely and soundly.
[en] Effect of the internal pressure on the corrosion behavior was investigated for the Zr nuclear fuel cladding tubes which were pressurized up to 2500 psi using Ar gas and corroded in steam of 1500 psi at 400 .deg. C. It was found that corrosion resistance of Zr fuel cladding tube was decreased with increasing the internal pressure although corrosion behavior at the early stage was similar irrespective of internal pressure. X-ray diffraction result on the oxide showed that crystal structure was not affected by the applied pressure of 2500 psi. SEM observation on the oxide surface revealed that a number of cracks elongated in axial direction were propagated from surface to interior in the case of 2500 psi. The degradation of corrosion resistance with internal pressure was attributable to the extensive cracking at the oxide surface, which is thought to be originated from the difference of ductility between Zr alloy and oxide when Zr fuel cladding tube was deformed due to the applied internal pressure. However, the increase of corrosion rate with internal pressure was shown to be relatively small. It was therefore suggested that the crack induced at the surface did not propagate to oxide layer in the vicinity of oxide/metal interface which is known to be protective to oxygen diffusion and to control the corrosion behavior